The present invention relates to a baby trailer and more specifically, to a foldable frame structure for baby trailer, which comprises a bottom frame, a first vertical side frame, a second vertical side frame, and a transverse top bar, wherein the front bar and rear bar of the bottom frame are retractable, facilitating adjustment; the rear bar has the two distal ends thereof respectively terminating in a respective angled end piece and respectively fixedly fastened to the side bars of the bottom frame by fastening members to reinforce the structural strength of the rear ends of the side bars so that wheels can be respectively and directly coupled to the side bars. Thus, the foldable frame structure is inexpensive to manufacture and can be collapsed to reduce the size, facilitating storage, packing or delivery.
U.S. Pat. No. 7,341,265 discloses a frame structure for foldable baby trailer. According to this design, when adjusting the front bar 81 and rear bar 82 of the bottom frame 8, it is necessary to unlock the four locking devices 91;92;93;94. Further, the two distal ends 821 of the rear bar 82 are respectively connected to the respective rear end of the left side bar 83 and the rear end of the right side bar 84. When the frame structure is folded up, the longitudinal distance between the front bar 81 and the rear bar 82 remains unchanged. Further, the wheels 87;88 cannot be directly coupled to the left side bar 83 and the right side bar 84. Affixing the wheel holder frames 85;86 to the left side bar 83 and the right side bar 84 to support the respective wheels 87;88 greatly increases the consumption of material and the manufacturing cost.
The present invention has been accomplished under the circumstances in view.
It is therefore the main object of the present invention to provide a foldable frame structure for baby trailer, which comprises a bottom frame, a first vertical side frame, a second vertical side frame, and a transverse top bar, wherein the front bar and rear bar of the bottom frame are retractable, facilitating adjustment; the first and second vertical side frames are respectively pivoted to the side bars of the bottom frame, each comprised of an arched top frame bar and two bottom frame bars. The arched top frame bar has two distal ends thereof respectively pivotally connected to respective top ends of the bottom frame bars with a respective pivot. Thus, the first and second vertical side frames can be collapsed and closely attached to the bottom frame, and the front bar and rear bar of the bottom frame can be received to shorten the width of the foldable frame structure
Further, the rear bar of the bottom frame has the two distal ends thereof respectively terminating in a respective angled end piece and respectively fixedly fastened to the side bars of the bottom frame by fastening members to reinforce the structural strength of the rear ends of the side bars so that wheels can be respectively and directly coupled to the side bars. Thus, the foldable frame structure is inexpensive to manufacture and can be collapsed to reduce the size, facilitating storage, packing or delivery.
Further, the angled end pieces of the inner tube and outer tube of the rear bar are respectively fixedly fastened to a respective rear part of the side bars of the bottom frame at a distance from the respective rear ends of the side bars. As, the rear bar is kept from the rear ends of the side bars at a distance, the size of the collapsed condition of the foldable frame structure can be further minimized, facilitating further storage, packing or delivery.